Citrus Scab

citrus-scabEarly scab pustules are a mixture of fungal and host tissue. These pustules are slightly raised and pink to light brown in color. Young foliar lesions superficially resemble young citrus canker and may have a slight water soaked margin. As fruit and leaf pustules develop, the small elevated pink spots become more defined and may form conical depressions nearby. As the pustules mature, they become warty and crack. Pustule color may progress to yellowish brown and eventually to a dirty grey. On lemons, tangerines, and sour orange, the growths are relatively raised. In contrast, on grapefruit the growths are flatter.

Serrano, D., Serrano, E., Dewdney, M., and Southwick, C. (2010). Citrus Diseases. USDA/APHIS/PPQ Center for Plant Health Science and Technology. [09-14]

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Citrus Chlorotic Dwarf Virus (CCDV)

chlorotic-dwarf-virusField symptoms consist of chlorotic flecking on young leaves, warping, crinkling, inverted cupping, spoon-shaping and variegation on leaves. Strong chlorosis and dwarfing of leaves are also observed. Grapefruit, lemon, mandarin and sour orange develop more severe symptoms than sweet orange. Diagnosis is made by grafting on rough lemon and Citrus macrophylla preferably in warm conditions

Serrano, D., Serrano, E., Dewdney, M., and Southwick, C. (2010). Citrus Diseases. USDA/APHIS/PPQ Center for Plant Health Science and Technology. [09-14]

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Citrus Black Spot

citrus-black-spotOlder lesions are small, round, sunken necrotic spots with gray centers. The lesions are bordered with a dark brown ring. Young lesions are small, reddish, and slightly raised. A yellow halo can be associated with the lesions. Foliar lesions are most commonly seen on lemons. They are rarely seen in well managed groves. Similar lesions can be seen on twigs and pedicles.

Serrano, D., Serrano, E., Dewdney, M., and Southwick, C. (2010). Citrus Diseases. USDA/APHIS/PPQ Center for Plant Health Science and Technology. [09-14]

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Citrus Alternaria Brown Spot

citrus-alternariaInitial foliar lesions occur on young tissue as small brown to black spots that develop prominent yellow halos. Lesions expand into irregular or circular necrotic areas which can involve large portions of the leaf, especially on highly susceptible cultivars like 'Minneola'. A fungal toxin is produced that can cause necrosis and chlorosis along the veins extending from lesions. Lesions are flat and visible on both sides on the leaf. Older lesions have a brittle paper-like texture in the middle of the lesions.

Serrano, D., Serrano, E., Dewdney, M., and Southwick, C. (2010). Citrus Diseases. USDA/APHIS/PPQ Center for Plant Health Science and Technology. [09-14]

Read more ...